1. Field of the Invention
The present invention relates to an organic electroluminescent (hereinafter referred to as EL) display.
2. Description of the Related Art
An organic EL display in which organic EL elements emitting white light and a color filter are used in combination is one of displays that can display a color image. Kashiwabara et al. describe in “Advanced AM-OLED Display Based on White Emitter with Microcavity Structure”, SID 04 DIGEST, pp. 1017-1019 that organic EL elements with microcavity structures, i.e., organic EL elements each having a function of an optical resonator are used in such an organic EL display.
When a microcavity structure is employed in an organic EL element that emits white light, a light component having a certain wavelength increases its intensity due to multiple-beam interference. That is, when a microcavity structure is employed in an organic EL element emitting white light, the light that the organic EL element emits outwardly changes from white light to colored light.
The wavelength at which intensity of light is increased is changed according to an optical length of the microcavity structure. Therefore, by individually setting the optical lengths of the microcavity structures in consideration of each coloring layer of the color filter, the wavelength of the light component with the maximum intensity that each microcavity structure emits can be matched with the wavelength at which the corresponding coloring layer of the color filter exhibits the maximum transmittance. Thus, according to the techniques, high degrees of efficiency and chroma can be achieved.
However, the present inventor has found the following facts in achieving the present invention. That is, an image displayed on the organic EL display is significantly dark when the image is viewed in an oblique direction as compared to the case when the image is viewed in the normal direction. In addition, the hue of the image displayed on the organic EL display changes when the viewing direction is changed from the normal direction to the oblique direction. That is, the organic EL display has high dependence of hue and luminance on the viewing direction despite the use of the color filter.